Thanks to ilovesaturn.com, here is a more extensive listing of event codes.

Code Event Code Description
1000 Order On Hold at Dealership
1100 Order Placed at Dealership
1101 Order Entered into System
1102 Order Entered via Web
2000 Order Accepted by Saturn
2001 Order Generated to Dealer
2005 Order Replaced with Prospec Order
2030 Order Edited by Saturn
2050 Order Changed
2500 Order Preferenced (or "Picked Up" or "Imaged")
3000 Order Accepted by Production Control
3100 Order Available to be Sequenced
3300 Order Scheduled for Production
3400 Order Broadcast (Internal Plant Order Produced)
3800 Vehicle Produced
4000 Vehicle Available to Ship
4104 Bailment Invoice Created
4B00 Bayed ("B", not 8)
4106 Bailment Released
4150 Vehicle Invoiced (Dealer Billed)
4200 Vehicle Shipped
4300 Intermediate Delivery
4V03 4V03 Estimated Delivery Date
4800 Rail Ramp Unload
5000 Vehicle at Dealer
6000 Vehicle Delivered to Customer
9000 Order Cancelled

and some more explanation on the standard codes...

Order status codes:
1100 = Preliminary Order (Order passed GM edit tables but dealers has not received allocation to place order)
2000 = Accepted By GM (Dealer used allocation to place order into production)
2500 = Preferenced (Order pulled to the production system)
3000 = Accepted By Production Control (Order input into the production system)
3100 = Sequenced (Order sequenced for Production)
3300 = Scheduled For Production (Order is scheduled into the plant build cycle)
3400 = Broadcast (Order is sent to various build & supplier areas to bring order together)
3800 = Produced (Order is built and VIN# shows in the Dealer Order system now)
4150 = Invoiced (Order is invoiced to the dealer)
4200 = Shipped (Vehicle is shipped to the dealer or point of delivery)
5000 = Delivered To Dealer
6000 = Delivered To Customer

There are other codes but they are almost exclusively used internally by GM and have no real effect on the status of the order as pertaining to the customer.